1. Field of the Invention
The present invention relates to CM22 type circuit breakers and CMD circuit breaker type enclosures and, more specifically to a retrofit assembly structured to allow a CM22 type circuit breaker to operatively engage a CMD circuit breaker type enclosure.
2. Background Information
Secondary power distribution networks consist of interlaced grids which are supplied by two or more sources of power so that the loss of a single source of power will not result in an interruption of service. Such secondary power distribution networks provide the highest level of reliability possible with conventional power distribution and are normally used to supply high-density load areas such as a section of a city, a large building, or an industrial site. Between a power source and the network is a transformer and a network protector. The network protector consists of a circuit breaker and a control relay. The circuit breaker includes at least one set of main contacts that move between an open position and a closed position. When the main contacts are closed, electricity may flow through the network protector. The control relay senses the transformer and network voltages and line currents then executes algorithms to initiate a breaker tripping or closing action. Trip determination is based on detecting an overcurrent condition or reverse power flow, that is, power flow from the network to the energy source. Network protectors are often found in dust-proof or moisture-proof housings, or vaults, which are disposed in subterranean passageways in large metropolitan areas. More specifically, an enclosure, or “tank,” is disposed with the vault and the network protector is disposed within the tank.
The network protector circuit breaker includes a number of other components such as, but not limited to, a bus assembly, an operating mechanism structured to move the contacts between the open position and the closed position, and a frame assembly. The circuit breaker bus assembly has a line assembly and a load assembly. The circuit breaker bus assembly line assembly includes at least one line bus that is coupled to, and in electrical communication with, the line side of the main contacts. Similarly, the circuit breaker bus assembly load assembly includes at least one load bus that is coupled, and in electrical communication with, the load side of the main contacts. The operating mechanism includes a closing device structured to move the main contacts to the closed position. Typically, a close device may be either a non-stored energy device, wherein a motor or other device closes the contacts, or a stored energy device, wherein springs, which are compressed by a motor or by a crank, are used to close the main contacts. The frame assembly supports the circuit breaker and is structured to engage the tank.
The tank includes a number of components that are coupled to the network protector components, or, that extend between the network protector and other elements of the power distribution network. For example, the tank includes a bus assembly having a line assembly and a load assembly. The tank bus assembly line assembly includes at least one line bus that is coupled to, and in electrical communication with, the power distribution network line conductor and is structured to engage the circuit breaker bus assembly line bus assembly. Similarly, the tank bus assembly load assembly includes at least one load bus that is coupled to, and in electrical communication with, the power distribution network load conductor and is structured to engage the circuit breaker bus assembly load bus assembly. The coupling between the network protector bus assembly and the circuit breaker bus assembly may be accomplished in several ways including a fixed connection, wherein the bus members are fixed to each other with a fastener, or, a primary disconnect, wherein one bus member is a stab and the other bus member has a jaw assembly that resiliently grips the stab.
The tank may also have a barrier assembly having at least one non-conductive member structured to be disposed between selected buses on either or both the tank bus assembly or the circuit breaker bus assembly. Further, there is typically an extendable rail assembly that allows the circuit breaker to be moved into, or out of, the tank. Each of these components, as well as others, are structured to operate/engage a specific type of circuit breaker.
That is, the tank is structured to have a specific type of circuit breaker with components in a specific configuration disposed therein. Each type of circuit breaker, while generally performing the same function, includes various different components. For example, a CM22 type circuit breaker includes a bus assembly having a line assembly and a load assembly having a fixed connection which is, for example, a bolted bus connection. That is, a CM22 type circuit breaker bus assembly is structured to be bolted to the tank bus assembly. Conversely, a CMD type circuit breaker bus assembly includes a primary disconnect assembly on each line and load bus. Each primary disconnect assembly includes a number of linearly aligned, opposing jaw members that are biased toward each other by springs. That is, the jaw members define a narrow gap. When a CMD type circuit breaker is moved into a tank, the tank bus assembly bus members, or stabs, are disposed within the gaps between the jaw members. To assist with the coupling/decoupling of the primary disconnects, a CMD type circuit breaker tank includes a levering mechanism that forces each primary disconnect assembly to slide over a tank bus assembly bus member. Thus, a tank structured to enclose/engage a CM22 type circuit breaker includes a tank bus assembly structured to be bolted to the CM22 type circuit breaker. A tank structured to enclose/engage a CMD type circuit breaker includes a tank bus assembly having buses structured to slide into a primary disconnect assembly. Further, the locations of the various bus members are different for different types of circuit breakers.
Other components of the different types of circuit breakers may have other differences. For example, a CM22 type circuit breaker utilizes a motor to close the circuit breaker contacts whereas the CMD type circuit breaker utilizes “stored-energy,” that is, a system of springs, to close the circuit breaker contacts. The tanks corresponding to such circuit breakers were adapted to actuate the relevant closing mechanism. For example, the tank for a CM22 type circuit breaker included an external switch structured to actuate the closing motor. Conversely, the tank for a CMD type circuit breaker did not have such a switch as the CMD type circuit breaker did not have a closing motor.
Thus, each type of circuit breaker was only structured to be placed in a tank having a corresponding configuration. Or, stated another way, each tank was adapted to accept a single type of circuit breaker. This is a disadvantage as users may like to swap out different types of circuit breakers in a single enclosure. For example, presently there are a number of CMD type circuit breaker tanks wherein users desire to install a CM22 type circuit breaker. There is, therefore, a need for a retrofit assembly and kit for a CM22 type circuit breaker structured to allow a CM22 type circuit breaker to engage, and be enclosed by, a CMD type circuit breaker tank.